coef.mdf {mudfold}

Generic coef method for S3 class "mdf" objects.

Description

This function extracts person and/or item parameters obtained after fitting MUDFOLD to binary preferential-choice data.

Usage

## S3 method for class 'mdf'
coef(object, type, ...)

Arguments

object

: A fitted object of class "mdf" obtained from the mudfold function.

type

: Argument that controls the type of parameters to be returned. If type="persons" (default), a vector with the person parameters is returned. When type="items" then a vector with the item ranks obtained by the MUDFOLD item selection algorithm is returned. If type="all" then a list with both person and item coefficients is returned to the user.

...

: not in use at the current version of the package.

Value

A vector when type="persons" or type="items". Alist when type="all".

Author(s)

Spyros E. Balafas ([e-mail])

References

W.H. Van Schuur.(1984). Structure in Political Beliefs: A New Model for Stochastic Unfolding with Application to European Party Activists. CT Press.

W.J. Post. (1992). Nonparametric Unfolding Models: A Latent Structure Approach. M & T series. DSWO Press.

W.J. Post. and T.AB. Snijders. (1993). Nonparametric unfolding models for dichotomous data. Methodika.

Examples

## load the ANDRICH data
data("ANDRICH")

## fit a MUDFOLD scale to the ANDRICH data
mudf_andrich <- mudfold(ANDRICH)

## obtain the parameters from the fitted object
coef(mudf_andrich)